JUMO 701150 14597 safetyM STB/STW - Safety Temperature Limiter and Safety Temperature Monitor Operating Manual - Manual (Page 39)

6 Safety Manual 39 2014-05-01
Safety function A function that is performed by an E / E / PE safety-related system, safety-related
system based on some other technology, or external equipment for reducing risk with
the goal of achieving or maintaining a safe state for the EUC taking into consideration a
specified dangerous event.
Safety integrity The probability that a safety-related system will perform the required safety function
under all specified conditions within a specified period of time according to
requirements.
Safety Integrity Level (SIL) One of four discrete levels for specifying the requirement for safety integrity of the
safety functions assigned to the E/E/PE safety related system. Safety Integrity Level 4
represents the highest level of safety integrity, while Safety Integrity Level 1 represents
the lowest.
Safety-related system A system that
- performs necessary safety functions that are required to reach or maintain a safe state
for the EUC and
- is designed by itself or with other E / E / PE safety-related systems of other
technology or external equipment for risk reduction to achieve the necessary safety
integrity for the required safety functions.
Safety Instrument System (SIS) Safety instrumented system to perform one or more safety-related functions. A SIS
consists of sensor(s), logic system, and actuator(s).
Lambda:
λ
Failure rate per hour
Lambda dangerous:
λ
D
Rate of dangerous failures per hour
Lambda Δ angerous Δ etect:
λ
DD
Rate of detected dangerous failures per hour
Lambda Δ angerous Υ ndetect:
λ
DU
Rate of undetected dangerous failures per hour
Lambda:
λ
S
Rate of safe failures per hour
Lambda:
λ
SD
Rate of detected safe failures per hour
Name Description